Jan. 14, 2011

The Poles, They Are A Changin'

A Florida airport recently had to close its main runway to repaint directional signs, due to the changing location of magnetic north. Over time, the location of magnetic north has shifted, with the magnetic north pole moving gradually towards Siberia. That shift made the airport signs, which reference a heading based on magnetic north, incorrect.

But what causes the magnetic field, and why is it shifting? The planet has undergone several magnetic polar reversals in its past, with north becoming south and vice versa. Are we due for another shift? We'll talk about the planet's magnetic field.